There are a number of different types of exercise apparatuses that exercise a user's lower body by providing a generally elliptical stepping motion. These elliptical stepping apparatuses provide advantages over other types of exercise apparatuses. For example, the elliptical stepping motion generally reduces shock on the user's knees as can occur when a treadmill is used. In addition, elliptical stepping apparatuses tend to produce a more natural foot motion than certain other types of exercise equipment. Examples of elliptical stepping apparatuses include U.S. Pat. Nos. 3,316,898; 5,242,343; 5,383,829; 5,499,956; 5,685,804; 5,759,136; 5,762,588; 5,779,599; 5,792,026; 5,899,833, 6,099,439, 6176,814, 6,217,486 and 6,846,272 along with U.S. Patent Application Publication No. 20050164837.
However, known elliptical stepping exercise apparatuses suffer from various drawbacks. As an example, most elliptical machines use at least one crank rotating about an axel fixed to the machine's frame, as exemplified by the various apparatus described in the above identified documents. As a result, either the elliptical machines do not closely correspond to a natural walking or running foot motion or elaborate mechanisms are used to compensate for the constraints of a fixed axel crank arrangement.